Adhesives for Blast Scenarios – Extreme Conditions for Structural Sealant Glazing

In the early days of the 1970s, Structural Sealant Glazing (SSG) technology was introduced in the U.S. to bond glass panels to metallic frames. Silicone adhesives were the only accepted bonding technology for this application due to the unique UV resistance and thermal stability they could offer, at that time. Considering that no options for controlling the UV radiation and temperature on the adhesive joint existed for façade design, the unique properties of silicone adhesives were essential. Compared to the past decades from the ‘70s to the ‘90s, the facade industry has experienced extraordinary technological developments: Nowadays numerous solutions exist to control temperature as well as UV radiation on façade components and bondlines. Consequently, new criteria for selecting the best performing adhesives available in the market should be used. Beyond silicone technology for SSG applications the benefits of other adhesives technologies and the new market requirements should be considered.
In this paper the mechanical and application properties of Sikaflex®-268, a high performance polyurethane adhesive are presented and compared to Sikasil® SG-500, a typical silicone adhesive used for structural glazing applications in facades. All obtained results illustrate that Sikaflex®-268 outperforms Sikasil® SG-500 and makes it an ideal solution wherever high loads need to be transferred. In blast scenarios, Sikaflex®-268 can introduce significant opportunities for reducing the SSG joint dimensions and optimizing systems. The PowerCure technology patented by Sika provides a combination of high flexibility for on-site bonding and reglazing with fast curing of the adhesive, widely independent of climate conditions. Furthermore, there are no limitations in terms of maximum joint dimensions in a single-step application with the boostered polyurethane technology.